(i) Field of the Invention
The present invention relates to a catalyst for asymmetric synthesis containing an optically active lanthanum compound.
(ii) Description of the Related Art
The present inventors have prepared an optically active lanthanum compound from a dilithium salt of an optically active 2,2'-dihydroxy-1,1'-binaphthyl and a trivalent lanthanum chloride under anhydrous conditions, and they have found that this compound is useful as a catalyst of an asymmetric nitroaldol reaction (announced in Symposium about Advancement of Reaction and Synthesis under the sponsorship of Japan Pharmaceutical Society on Nov. 7, 1991).
However, the reaction yield or the asymmetric yield of the optically active lanthanum compound cannot be reproduced at all. Although the asymmetric nitroaldol reaction is substantially an extremely useful reaction for providing an important synthetic raw material for a physiologically active compound, its usefulness cannot be sufficiently utilized. Thus, in order to industrially prepare a medicine which is effectively manufacturable only by the asymmetric nitroaldol reaction, it is necessary to develop a catalyst for asymmetric synthesis having the high reaction yield and the asymmetric yield as well as the reproducibility.